Cured and finished buds as well as growing medical marijuana plants propagated at a medical marijuana growing operation in Washington in September. (Linda Davidson/The Washington Post)

Tuesday was a banner night for medical marijuana — with ballot initiatives in numerous states widening access to the substance for Americans seeking relief from pain or a treatment for illness.

Massachusetts and California, where Napster co-founder and cancer philanthropist Sean Parker helped fund a campaign to legalize the drug, were among the states passing new recreational marijuana laws. The tide also turned in Florida, North Dakota and Arkansas — where similar measures were defeated in the past — and in Montana where measures regarding medical marijuana were passed. Before this week, medical marijuana was legal in a little over half the country or 25 states.

The wins come as rigorous scientific evidence is mounting that marijuana or its components may have beneficial medical effects. Earlier this year, GW Pharmaceuticals said that clinical trials show a cannabis-derived drug may be able to reduce seizures in patients with Dravet syndrome, a rare and severe form of epilepsy. Physicians are also increasingly looking to marijuana as an alternative to highly addictive opioids that have led to a crisis in overdoses. This chart, from my colleague Christopher Ingraham, shows just how dramatic the difference in the painkiller prescriptions is in medical-marijuana states vs. non-medical-marijuana states.

Florida: A similar measure was narrowly defeated two years ago. This time, voters cast their ballots overwhelmingly in favor of a full-scale medical marijuana program. The new amendment states that patients with illnesses of the “same kind or class as or comparable to” serious illnesses, such as cancer, HIV, post-traumatic stress disorder, Parkinson’s disease and epilepsy would be eligible to access medical marijuana. Some 450,000 residents would qualify, according to The News-Press in Fort Myers. The state already had laws on the books that allowed the use of marijuana for the terminally ill and of a cannabis-derived drug for epilepsy.

North Dakota: According to the Bismark Tribune, “The measure will allow people to possess up to 3 ounces of medical marijuana for treatment of up to nearly a dozen medical conditions. Facilities for medical marijuana distribution will be licensed by the state Health Department and operated by nonprofit organizations.”

Montana:The Independent Record in Helena reported that the measure means that “providers of the drug will not be limited to the number of patients they can serve:”

“The previous restriction imposed a limit of three, which was sharply opposed by patients and providers in the program. Most medical marijuana patients were left without a registered provider under the restrictions. Since they went into effect, patients have left the program. More than a third of patients registered in September left over the next month — 7,785 remained in October, according to the state health department.

Arkansas: The measure allows people who have any of 18 qualifying conditions — such as cancer, glaucoma, Tourette's syndrome, Alzheimer's disease and hepatitis C — to access dispensaries. According to the Associated Press and KTHV, “some political leaders said they preferred that Arkansas legislators instead allow a version of the drug that is low in THC, which gives marijuana its high.”

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